Fuel injection device for internal combustion engines



Nov. 9, 1943. H, LlEBERi-lERR 2,333,944

FUEL INJECTION DEVICE FOR INTERNAL COMBUSTION ENGINES Filed Aug. 18, 1941 2 Sheets-Sheet 1 BY [2 ATTRNES H. LIEBERHERR Nov. 9, 1943.

FUEL INJECTION DEViCE FOR INTERNAL COMBUSTION ENGINES Filed Aug.

13, 1941 2 Sheets-Sheet 2 Patented Nov. 9, 1 943 4 UNITED STATES PATENT OFFICE FUEL INJEUI'ION DEVICE FOR COMBUSTION ENGINES Hans Lieberherr, Wintertliur, Switzerland, as-

signor to Sulzer Freres, Societe Anonyme, Wintertliur, Switzerland Application August 18, 1941, Serial No. 407,310 In Switzerland August 1'], 1940 2 Claims. (Cl. 123-139) (Granted under the provisions of sec. 14, act of March 2, 1927; 357 0. G. 5)

This invention relates to a fuel injection demined. The drive of the control member can be vice for internal combustion engines having 8. arranged in such a way that it cannot possibly fuel injection pump operated by the gas pressure remain fixed in the open position. By employing in the working cylinder. a control cam or control eccentric, symmetrically It is known how to effect the injection of fuel; 5 designed and set with the axis of symmetry at in internal combustion engines by a stepped pisthe dead center of. the working piston, and by ton which on the one hand is subject to the gas changing the point of injection by means of a pressure in the interior of the cylinder and on swinging roller, the engine may be controlled the other hand delivers the fueltoaspring-loaded with one and the same control cam or control valve. Since the injection with such a device eccentric when runningin either direction. begins at the moment in which the fuel pres- In the fuel injection device an accumulating sure is equal to the opening pressure of the fuel piston may also be provided; the fuel supplied by valve, but the fuel pressure increases with ina separate pump is delivered to it at any desired creasing load because the gas pressures in the moment during the stroke, and it transfers the cylinder then increase, injection at high load fuel into the pneumatic fuel pump when the takes place considerably sooner than at low load, pressure in the cylinder falls. The accumulating a condition which is not'desirable because of the space maybeprovided with an overflow controlled acceleration in the rise of pressure in the cylinby the accumulating piston, and this overflow der. may be of such dimensions that it is not able to This defect has been got over by increasing take any more fuel than the filling required for the spring loading of the valve in. accordance one single injection at overload.

with the increasing load on the engine. But this In the accompanying drawings: v gave rise to the new drawback that the pressure Fig. 1 ma sectional side view of a fuel'injection under which the first drops of fuel enter the device embodying'the invention, and

cylinder changes with the load, and consequently Figs. 2 to 5 illustrate various positions of the the first initial combustion which is of the greatdevice of Fig. 1. est importance for the later combustion, is neces- In the internal combustion cylinder I, closed sarily impaired. In addition to that, regulation by the cylinder cover 2, a piston 3 is shown in of the fuel valve springs in accordance with the upper dead center. The cylinder l'is inserted in load on the engine must be provided. a jacket 4 and surrounded by a cooling-medium An endeavour has been made to get over this circulating through the space 5. The cylinder drawback by mechanical control of the fuel valve cover 2 carries the spring-loaded automaticallyneedle. In this way it is possible to fix the moment of fuel injection exactly, but not to control P working fuel injection pump 1, and the control the starting of the combustion, since there is no m mb r 8 having a, casing 8' and the piston direct relation between the moment of injection v lv 9.

and the pressure in the fuel pipe. In addi The gases in the combustion space l0 pass t t at. th m m nt f termination r the iniecthrough the passage ll into the fuel pump 1 and tion is fixed by such an arrangement. It is conact o the gas piston l2 and pump piston l3. A sequently necessary here also to control the 40 spring I4 is provided between the gas piston l2 needle in accordance with the load. and pump piston l3. Using a spring l4 acting The invention compri e a Spring-loaded autoon the piston l3 in the same direction as the gas matic fuel v lve. an the f l p is connected 7 pressure, has the advantage that the fuel presto the fuel valve by a control member which desure changes much less during the injection than termines the b nn f h nje n Wi h if the fuel pump piston was only under the inthis' arrange n at any load, and also with e fiuence of the gas pressure. In fact, the gas presacting fuel injection valve 6, the pneumatically engine running in one direction or the other, the sure is least when the piston I2 is in its lowest injection is started at the suitable moment and position, and then, on the other hand, the tension stopped again at t e time When t e f P s u of spring i4 is the greatest. The contrary is the has fallen below the closing pressure of the valve. se when piston I3 is in its highest position.

consequently there is no annoying late dribbling An accumulating space 5 is connectedwith from the valve. In addition to that, the dia e the fuel pump I and it receives the fuel through of the gas piston is such that the pressure caused a separate fuel pump not shown in the drawings, in the fuel piping is co s de ably greater than the the fuel being passed into the accumulating "space opening pressure of the fuel valve, even at lowest [5 through the pipe l6 at any desired moment load. Perfect starting of the combustion'is conduring a revolution of the engine. When the sequently ensured under all conditions of workpressure under the gas piston l2 has fallen sufing. ficiently low, a spring I l forces theaccumulating By gradually opening the control member, the piston l8 downwards. The fuel flows through rate at which combustion starts can be deterthe valve l9 into the space I 9'.

, 21 has a roller 21a engaging cam Whenthe pump 1 is making a delivery stroke,

the fuel enclosed in the delivery Chamber of the pump and'in the pipe 2| is at first compressed. When the control member 8 is opened, the delivery valve 29 is now fully opened, and the fuel is injected into the combustion space throughthe pipes 2|, 2| and the injection valve 5. The injection valve 6 has a needle 22 which is loaded by a spring 23.

In the accumulating space IS an overflow 24 is provided which is of such dimensions that it does not take more than the fuel required for one'single injection at overload and it allows the superfluous fuel to escape. In this way dangerous pressures in the fuel pipes are prevented.

.- The piston valve 9 of the control member 8 isoperatedfrom a control shaft 26 througha allows the moment of swinging link 21 which injection to be changed in accordance with the load. The shaft 26 may be set by any suitable.

control means such as a manually operated lever or a servomotor (not shown). The swinging link camshaft 29. The eccentric 30 fixed to the shaft 33 turns in the shaft 3|a which is connected at one end 3| with the piston valve 9 and at the other end 32 with the swinging link 21. The pivot on which lever 3la rocks may be adjusted by the eccentric 30. The eccentric shaft 33 for instance may be coupled to the starting device in such a way that the control piston 9 is pressed down so far during the starting period that no fuel can flow to the fuel valve 6.

The apparatus operates as follows: The fuel required for one injection is measured by a separate fuel pump not shown in the drawings and delivered through the pipe l6 into the accumulating space at any desired moment during a I revolution of the engine. The accumulating piston I8 is loaded by a spring l1. When the pressure below the gas piston l2 has fallen sufiiciently low, the spring ll causes the fuel to be transferred into the injection pump. The piston I3 is connected to the gas piston |2,'whi'ch is .alwayssubjected to the gas pressure in the combustion space III of the engine through the passage H. The piston I2 is continually pressed upwards by the spring H independent of the pressure in the cylinder.

Under the influence of the 'gas pressure in the cylinder, the fuel contained in the pump 1 and pipe 2| is compressed. At a suitable moment, generally shortly before the piston reaches its upper dead center, the piston valve. 9 opens the outlet to the fuel valve. The swinging link 21 andits roller 21a are raised by the cam 28, the piston valve 9 moves downwards, and the connection between pipe 2| and piston valve 9 is interrupted.

If for any reason piston valve 9 should stick, the fuel will collect in the accumulating space l5 and keep raising the piston I8 until the overflow opens. Then the accumulating piston l9 at i t e same time assumes the functions of a safety- Under certain circumstances it may be valve.

to control the downward movement of advisable 28 fitted on the groove on the piston valve 9 being designed in such a way that at'ilrst only a small cross-sectional area is available for passage of the fuel.

, in the the accumulating piston l8 by means of a damper I of the spring or liquid type.-

The piston valve 9 may be opened gradually in order to control the rate at which combustion starts, the cam 28 for instance being designed as an eccentric, or the profile of the annular Also the control of the piston valve 9 is arranged in such away that it cannot possibly remain stuck inv the open position, since it is forced mechanically into the closed position. By' using a control eccentric 29, symmetrically designed and set with the axis of symmetry at the dead center of the working piston, and by of injection by means of the swinging link 21, the running of the engine in either direction is controlled by'me'ans of one and the same control cam.

Fig. 2 shows the position of the piston valve 9 shortly before fuel can pass through at 40 from pipe 2| to fuel valve 6. In Fig. 3 the position of the piston valve 9 is shown when the piston 3 is in, the neighborhood of its lower dead center;

Fig. 4 shows the position of the piston valve 9 when the engine is running backwards, the swinging link 21 being brought back into the position symmetrically to the control cam 29 in the ahead position by turning the regulating shaft 28. The piston valve 9 has already half uncovered the opening 40 which connects fuel valve 6 to pipe 2|.

During the starting period (Fig. 5) the piston valve 9 can no longer uncover the opening 40 when the starting shaft 33 is rotated. This prevents any highly compressed starting air and fuel from entering the cylinder space I0 simultaneously and causing misfiring. The starting shaft 33 is again turned back as soon as the engine has been set in motion by the starting air.

I claim:

1. In a fuel injection device for internal combustion engines having a fuel injection pump with a gas piston operated by the gas pressure in the engine cylinder, the improvement which comprises a spring in engagement with the fuel pump piston which forces the piston in the same direction as the gas pressure acting on the gas piston, a spring-loaded automatic fuel valve for injecting liquid fuel into the engine, a duct for the passage of fuel from the injection pump to the automatic fuel valve, a control member controlling the passage of fuel in the duct, and means operated in timed relation with the engine pistons for caus-. ing the control member to determine the beginning of fuel injection.

2. A fuel injection device for internal combustion engines which comprises a fuel pump having a fuel pump-piston connected to and driven in part by a gas piston driven by gas from the engine cylinder and a spring connected to the fuel pump piston which forces the fuel pump piston in the same direction as the gas piston, an injection valve for delivering liquid fuel into the enginecylinder, a duct connecting the'fuel pump with the injection valve, a control valve duct controlling the admission of fuel to the injection valve, a lever arranged to operate the control valve, a cam driven by the engine, a swinging link interconnecting the lever with the cam, and an adjustment means attached to the swinging link whereby changes in the position of the swinging link may effect the timing of the movement of the control valve with re- HAN S LIEBERHERR.

changing the point 

